Pump with variable output and constant number of strokes



Sept. 16, 1924.

G. SILVESTRI PUMP WITH'VARIABLE OUTPUT AND CONSTANT NUMBER OF STROKES Filed Jan. 12. 1921 2 Sheets-Sheet l Sept. 16, I924.

G. SILVESTRI PUMP WITH VARIABLE OUTPUT AND CONSTANT NUMBER OF STROKES Filed Jan. 12, 1921 2 Sheeis -Sheet 2 Patented Sept. 16, 1924.

PATENT FFHCE.

GIULIO SILVESTRI, OF RODAUN, NEAR VIENNA, AUSTRIA. Y

' PUMP WITHV ARIA B1LE OUTPUT AND CONSTANT NUMBER OF STROKES.

Application filed January 12, 1921. Serial No. 436,793.

To all whom it may concern:

Be it known that I, GIULIo SIL Es'rRI, a citizen of Austria, residing at Rodaun, near Vienna, in Austria, have invented a new and 5 useful Improvement in Pumps with Variable Output and Constant Number of Strokes (for which I have filed applications in Austria April 18, 1914, Patent N 0. 73854 of December 15, 1916; Sweden, February 24, 1917, Patent No. 46409; Norway, August Denmark,-

10, 1917, Patent No. 36096; August 10, 1917, Patent No. 24543 of May 7, 1919; Spain, March'20, 1920, Patent No.

73028 of August 2, 1920; Czechoslovakia,

April 10, 1920, Patent No. 2619; Poland, May 4, 1920, application No. 6407/1920; Switzerland, July 1, 1920, Patent No. 93654; France, July 7, 1920, Patent. No. 519321; Belgium, July 8, 1920, Patent No. 288827; Italy, July 21, 1920, Patent No.*189593; Hungary, August 16, 1920, application N 0. 10587; Germany, May 1, 1914, N 0. 314380), of which the following is a specification.

The present invention relates to an anrangement for varying the output and the direction of flow of reciprocating pumps without changing the number of strokes or the length of the stroke of the piston. The

said variation is attained in' well-known man- 1 nor by drawing. a quantity of liquid from the delivery pipe into the pump cylinder during the suction stroke, and returning said quantity of liquid into the suction pipe during the delivery stroke. The invention consists broadly in this, that between the pum' cylinder on the one hand and the suction and delivery pipes on the other hand there is provided a regulating member controlling the communication between the pump cylinder and the said pipes and rotating at a number of revolutions corresponding tothe number of strokes of the piston, which member alternately puts the pump cylinder in communication with the suction pipe and the delivery pipe, and which, from the normal adjustment at which the pump cylinder communicates with the suction pipe during the entire suction stroke and with the delivery pipe during the entire delivery stroke, may be adjusted to rotate more or less in advance of or after the pump piston.

The advanta e of this arrangement lies in the very considerable simplification of. the pump which needs only a single rotating regulating member, which not only pertakes over the function of the suction and pressure valves otherwise necewary, and, finally, which also determines the direction of flow of the delivered liquid, so that a special, reversing device also becomes unnecessary. Moreover, the casing in which the regulating-member rotates may be arranged separate from the pump itself, and the regulating member need only be driven at a number of revolutions corresponding to the number of strokes of the piston,'so that the arrangement may easily be applied to any existing pumps.

The invention is illustrated in the accompanying drawings in which Fig. 1 shows a lift pump with a crank and a controlling or regulating member which operates according to the method described, Fig. 2 shows the corresponding regulating member in longitudinal section and Figs. 3 to 17 are dia rammatic illustrations of different wor ing positions of the various parts with different deliveries of the pump.

For the sake of simplicity and easier understanding of the invention a single acting lift pump has been selected for illustration but the invention is in no way limited to such pumps. 7

In the drawings a denotes the pump cylinder, b the pump piston which is driven by the piston rod 0 and the crank d from the shaft 6. From the pump a pipe or a passage leads to a casing g in which the regulating member or valve it rotates. This member or valve possesses at opposite points chambers 11 and k running axially of which the one chamber 2' is continuously in communication through a port l and an annular chamber t in said valve h with the suction pipe m, the other is being continuously in communication through a port u and an annular chamber 'v in said valve h with the delivery pipe 02 of the pump. The outlet of the passage f into the casing g is made wide enough to enclose an anglewhich is equal to that enclosed by the radii to the adjacent edges of the chambers i and 7c of the regulating member.

The regulating member 1 is driven at a suitable ratio to :the shaft e. The transmission .ratio is dependent on the number of the present illustration only two chambers tion with the the crank throughl35.

are provided in the regulating member.

The regulating member can however be rotated independently of the rotation about its axis, as,.for instance, by driving the valve or member 71. from the crank shaft 6 by means of a chain m and by adjusting the driving sprocket y on crank shaft e into different positions in which it may be secured by means of the set screw 2, as illustrated diagrammatically in Fig. 1. By this displacement is determined whether the opening of the chambers c' and is to the passage f coincides or not with the commencement of the suction or delivery stroke of the pump piston.

The pump operates at full output when the opening phases of the chambers exactly coincide with the hases of movement of the piston, i. e. when the chamber i communicating with the suction pipe m at the beginning of the suction stroke of the piston and the chamber is communicating with the delivery pipe 11. at the beginning of the pressure stroke open to the pump passage and close at the end of these strokes. he modus operandi of the arrangement with this adjustment of the regulating member h is clear from Figs. 1 to 5. Fig. 1 shows the position of piston and regulating member at the beginning of the suction stroke Fig. 3 shows them in [the position in which the piston is moving at its greatest speed during the suction stroke; Fig. 4 shows them at the point of change of stroke, and Fig. 5 shows them in the position in which thepiston is moving at maximum speed 'during the delivery stroke. If the regulating member is now so adjusted that'the chamber 2' opens before the piston has commenced its suction stroke and the chamber k opens before the piston.

has commenced its delivery stroke a reduction of the output takes place. In Figs. 6 to 9 a lead of 45 is assumed.

llt is to be observed that with this adjustment the pump is in communication with the suction pipe m only during that part of the suction stroke of the piston which corresponds to a movement of the regulating member through 135. The pump piston has, however, still to complete the remaining orti'on of'its suction stroke. During this interval the pum is already in communicadellivery pipe 12. through the chamber is. The pump thus operates during this portion of the suction stroke as an engine, and it uses a portion of the fluid which it takes from the delivery pipe 01., and transmitsthe corresponding work to the driving shaft 0.. On completion of the change of stroke the pump supplies to the delivery pipe untilithe chamber 74* closes the passage f which again correspondsto a rotation of ln the last part of I the delivery stroke the pump is again in s communication with the suction pipe. The pump thus forces into the suction pipe a mosses quantity of liquid which is equal to the quantity removed at the end of the suction stroke from the delivery pipe. The output of the pump is thus reduced by that amount which it receives at the conclusion of the suction stroke from the delivery pipe, and by that amount which at the end of the delivery stroke it delivers to the suction pipe. With a lead of the regulating member of 15 these two quantities amount to about 15%. The pump supplies only about of its capacity although the number of strokes remains unaltered.

The output falls off rapidly with the increase in lead and is reduced to zero when the lead amounts to 90, as will be clear from Figs. 10 to 13. In this case the pump takes liquid from the suction pipe only during the first half of the suction stroke. During the second half of the suction stroke it alike the output of the pump is nil. llf the regulating member is given a greater lead, say to 135, Figs. 14-17, an increase in the output again takes place, but the direction of movement of the liquid set in movement by the pump is reversed.

As shown in'Fig. 14, the pump actually takes liquid from the suction pipe at only during a crank rotation of 45. During the further rotation of the crank through 135 the pump is under the influence of the liquid in the delivery pipe at and runs as an engine or removes liquid. On the succeeding delivery stroke the pump delivers liquid only during one crank rotation through 45 into the'delivery pipe n and the remainder passes into the suction pipe m. As, thus, a larger quantity of liquid is removed from the delivery pipe and this is forced into the suction pipe reversal of the feeding device of the pump, takes place.

This possibility of reversal which always must succeed azero output of the pump is "of great value when the liquid supplied by the pump is used for driving an engine since such an arangement permits the engine ,to run in both "directions with any suitable velocity without efiecting any alterations to the pump or its drive.

If the regulating member is ailj usted" topassages m and n during this time on the suction stroke in the pump cylinder a partial vacuum and on the delivery stroke an increase of pressure must take place.

The partial vacuum can be neglected. In

order, however, to obtain more uniform load- 7 ing of the driving machine for thepump and also to avoid the .slightlosses of liquid caused thereby there is, provided on the connects.

These two valves act thus as safety valves in order that the quantity of liquid supplied by the pump actually passes wholly into the delivery -pi e of the pumpand undesired eflects are usactually avoided.

I'claimi f a 1 1. A pump, a deliveryand a suction pipe associated therewith, means for. withdrawing a quantity of liquid from said delivery pipe upon the suction stroke of said pumpand forcing an equal quantity of hquid 'into said suction pipe upon "the succeed ng delivery stroke, and means for adjusting said other means whereby the output of said pump may be varie operation thereof. v

2. A pump of the kinddescrib'ed havin a suction and a delivery pipe associate therewith, and a controlling device adapted to run at a suitable ratio to the number of strokes of said :pump, said device being adapted to serve both saidsuction pipe and said delivery pipe and being adjustable so that the phases of o ening of said suction and delivery pipes coincide with the suction and pressure phases of said pump or are advance of or behind the same;

'3. A pump of the kind described having a suction pipe and a delivery pipe, a piston operable in said pump, and a controlling device associated therewith and operable at a suitable ratio to the number'of strokes of said piston,- said device being adapted to serve both said suction pipe and said delivery pipe and being adjustable so that the phases of opening of said suction and delivery p pes coincide with the suction and pressure phases of saidpump pistonor are in advance of or behind the same, the pump chamber of said pump being connected with said suction and delivery pipes by branch pipes, one of said-branch pipes having an overflow non-return valve opening' to the pump chamber, said other branch pipe havng a valve opening to said delivery pipe,

Therefore, the pump isduring" the uniiorin.

said valves afl'ording an auxiliary path free from resistance to the liquid. I

4. In an arrangement for varying the output and thedirection of flow of reciprocating pumps without changing the number of strokes 'or the length of the stroke of the piston, the combination of a pump cylinder,

a reciprocating piston in said cylinder, a

suction pipe, a delivery pipe, a movable regulating member interposed between said 'pump cylinder on the one hand and said suction and delivery pipes on the other hand, said regulating member controlling the communication between thepun'ip cylinder and said pipes and being adapted to'put thepump cylinder in communication alternately with the suction pipe and with the delivery pipe, means for operating said regulating member at a number of strokes corresponding to the number of strokesof said piston, and means for adjusting said regulating member to operate .-more or less in advance of 'or after said piston in' relation to its normal adjustment at-which-said pump cylinder communicates with said-suction pipe during the entire suction stroke of said piston and with said delivery pipe during the entire delivery stroke.

5. In an arrangement for varying the out- .put and the direction of flow of reciprocat-" ingpumps without changingithe'number of strokes or. the lengthfof the stroke of the piston,.the combination of a ump c' linder, a

reciprocatingpiston in sa i cylin er, a suction pipe, a delivery'pipe, a movable'regulating member interposed between said pump cylinder on the one hand and said suction anddelive-ry. ipes on the other hand,

,said regulating mem er controlling the communication between the pump cylinder and said pipes and being adapted 'to put the pump cylinder in communicationalternately with the suction pipe and with the delivery pipe, means for operating said regulating member at a number of strokes corresponding to the numberof strokes of said piston, means for adjusting said regulating member to operate more or less in advance of on after said piston in relation to its normal adjustment at which said pump cylinder communicates with said suction pipe durin the entire suction stroke of said piston and with said deli-very pipe during the entire delivery stroke, an auxiliary plpe connect- "ing said pump cylinder with said suction pipe, a back valve in said auxiliary pipe opening towards the pump cylinder, a sec- 0nd auxiliary pipe connecting the pump-- cylinder Wlthllhfi delivery pipe, and a back valve in said second auxiliary pipe opening towards said delivery pipe. Y

GIUL Io SILVESTRI. 

